The present invention relates to a novel transition metal compound, a catalyst component for xcex1-olefin polymerization comprising the transition metal compound and a process for the preparation of an xcex1-olefin polymer in the presence of the catalyst component. More particularly, the present invention relates to a highly active catalyst component which allows the preparation of a high molecular and high melting xcex1-olefin polymer, a polymerization catalyst comprising such a catalyst component and a process for the preparation of an xcex1-olefin polymer in the presence of such a catalyst.
A so-called Kaminsky catalyst well known as uniform catalyst for olefin polymerization exhibits a high polymerization activity and thus allows the preparation of a polymer having a sharp molecular weight distribution.
As transition metal compounds for use in the preparation of an isotactic polyolefin in the presence of a Kaminsky catalyst there are known ethylenebis(indenyl) zirconium dichloride and ethylenebis(4, 5, 6, 7-tetrahydroindenyl)zirconium dichloride (as in JP-A-61-130314 (The term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d)) . However, the preparation of a polyolefin in the presence of such a catalyst is normally disadvantageous in that the resulting polyolefin has a small molecular weight and, if low temperature polymerization is effected to obtain a polymer having an increased molecular weight, the catalyst exhibits a reduced polymerization activity.
Further, for the purpose of preparing a high molecular polyolefin, a method has been proposed involving the use of a hafnium compound instead of the foregoing zirconium compound (Journal of Molecular Catalysis, 56 (1989), pp. 237-247). However, this proposed method is disadvantageous in that the catalyst used exhibits a low polymerization activity.
Moreover, dimethylsilylene bis-substituted cyclopentadienyl zirconium dichloride has been proposed (as in JP-A-1-301704, Polymer Preprints, Japan 39 (1990), pp. 1,614-1,616, JP-A-3-12406). Dimethylsilylene bis(indenyl) zirconium dichloride has been proposed (as in JP-A-63-295007, JP-A-1-275609). The use of these compounds allows the preparation of a polymer having a high steric regularity and a high melting point in a relatively low temperature polymerization process but provides a polymer having a low steric regularity, melting point and molecular weight under high temperature polymerization conditions which are economical. On the other hand, a catalyst comprising a transition metal compound comprising halogen atoms introduced into substituents on the atoms crosslinking ligands and a co-catalyst has been proposed (as in JP-A-4-366106). However, such a catalyst is disadvantageous in that it provides a polymer having a low molecular weight and steric regularity as compared with similar catalysts free of halogen atoms.
Further, a compound has been known having enhanced isotacticity and increased molecular weight provided by adding substituents to indenyl group which is part of ligands (as in JP-A-4-268307, JP-A-6-157661). Moreover, a transition metal compound has been known wherein a subring containing two adjacent carbon atoms constituting a conjugated 5-membered ring has members other than 6 (as in JP-A-4-275294, JP-A-6-239914, JP-A-8-59724).
However, the foregoing compounds exhibit an insufficient catalytic action under high temperature polymerization conditions that are economical. Further, these compounds give a catalyst system soluble in the reaction medium in most cases. Accordingly, the resulting polymer has an amorphous grain form and a small bulk density and contains much fine powder and thus exhibits extremely poor grain properties. Accordingly, these compounds have many production disadvantages. For example, if these compounds are used in slurry polymerization or gas phase polymerization, continuous stable operation can be hardly conducted.
In order to solve these problems, on the other hand, a catalyst comprising a transition metal compound and/or organic aluminum compound supported on an inorganic oxide (e.g., silica, alumina) or organic material has been proposed (as in JP-A-61-108610, JP-A-60-135408, JP-A-61-296008, JP-A-3-74412, JP-A-3-74415). However, polymers prepared in the presence of such a catalyst contain much fine powder or coarse grains. Further, these polymers exhibit insufficient grain properties, e.g., low bulk density. Moreover, such a catalyst exhibits a low polymerization activity per unit solid component. Further, such a catalyst provides a polymer having a relatively low molecular weight and steric regularity than a catalyst system free of carrier. The present invention has been worked out under these circumstances.
An object of the present invention is to provide a novel transition metal compound which can form a catalyst component for xcex1-olefin polymerization capable of producing a high molecular and high melting olefin polymer that can be extruded or injection-molded in a high yield.
Another object of the present invention is to provide a catalyst for xcex1-olefin polymerization comprising the foregoing catalyst component and a process for the preparation of an xcex1-olefin polymer in the presence of such a catalyst component.
A further object of the present invention is to provide a novel catalyst component which is little liable to deterioration of performance when used supported on a carrier to improve its process applicability.
A first aspect of the present invention lies in a novel transition metal compound represented by the following general formula (I): 
In the general formula (I), R1, R2, R4 and R5 each independently represent a hydrogen atom, C1-10 hydrocarbon group, C1-18 silicon-containing hydrocarbon group or C1-18 halogenated hydrocarbon group.
R3 and R6 each independently represent a C3-10 saturated or unsaturated divalent hydrocarbon group which is condensed with the 5-membered ring, with the proviso that at least one of R3 and R6 has from 5 to 8 carbon atoms and hence forms a 7- to 10-membered condensed ring.
R7 and R8 each independently represent a C1-20 hydrocarbon group, C7-30 oxygen-containing aryl group, C7-30 nitrogen-containing aryl group or C7-30 sulfur-containing aryl group, with the proviso that at least one of R7 and R8 is a C7-30 oxygen-containing aryl group, C7-30 nitrogen-containing aryl group or C7-30 sulfur-containing aryl group.
The suffixes m and n each independently represent an integer of from 0 to 20, with the proviso that m and n are not 0 at the same time and if m or n is an integer of not less than 2, R7""s or R8""s may be connected to each other in arbitrary positions to form a new cyclic structure.
Q represents a divalent C1-20 hydrocarbon group, halogenated hydrocarbon group or silylene, oligosilylene or germylene group which may have C1-20 hydrocarbon or C1-20 halogenated hydrocarbon group, which group connects the two 5-membered rings.
X and Y each independently represent a hydrogen atom, halogen atom, C1-20 hydrocarbon group, C1-20 silicon-containing hydrocarbon group, C1-20 halogenated hydrocarbon group, C1-20 oxygen-containing hydrocarbon group, amino group or C1-20 nitrogen-containing hydrocarbon group.
M represents a transition metal element belonging to the groups 4 to 6 in the periodic table.
A second aspect of the present invention lies in a novel transition metal compound represented by the following general formula (II): 
In the foregoing general formula (II), R1 and R4 each independently represent a C1-6 hydrocarbon group, C1-6 silicon-containing hydrocarbon group or C1-6 halogenated hydrocarbon group.
R2 and R5 each independently represent a hydrogen atom or C1-6 hydrocarbon group.
Q, M, X and Y are as defined in the general formula (I).
R9, R10, R11, R12, R13, R14, R15 and R16 each independently represent a hydrogen atom or C1-20 hydrocarbon group.
Ar1 and Ar2 each independently represent a C7-30 oxygen-containing aryl group, C7-30 nitrogen-containing aryl group or C7-30 sulfur-containing aryl group.
A third aspect of the present invention lies in a catalyst component for xcex1-olefin polymerization comprising a transition metal compound represented by the foregoing general formula (I) or (II).
A fourth aspect of the present invention lies in a catalyst for xcex1-olefin polymerization comprising the following components (A) and (B) and optional component (C):
Component (A): Transition metal compound represented by the general formula (I) or (II);
Component (B): Compound selected from the group consisting of aluminumoxy compounds, ionic compounds capable of reacting with Component (A) to convert Component (A) to cation and Lewis acids; and
Component (C): Particulate carrier
A fifth aspect of the present invention lies in a catalyst for xcex1-olefin polymerization comprising the following components (A) and (D) and optional component (E):
Component (A): Transition metal compound represented by the general formula (I) or (II);
Component (D): Compound selected from the group consisting of ion exchangeable layer compounds excluding silicate or inorganic silicates; and
Component (E): Organic aluminum compound
A sixth aspect of the present invention lies in a process for the preparation of an xcex1-olefin polymer, which comprises allowing an xcex1-olefin to come in contact with any one of the above-described catalysts to cause polymerization or copolymerization thereof.